Website gives you a world wide presence. Web Surfers all around the globe can visit your website. If you have a website written in UK or International English, you might have different English than that of USA. There are certain words in English which are spelt or spelled differently in US, UK, Australia and various other countries in the world. Words like humor, license and generalize can be right in UK form of English but will be wrong for US. Hence English spellings differ from country to country. You might receive emails from visitors about spelling errors, which they found incorrect in your website. Again this depends on the spoken English of your visitor.
Website, where surfers search your site through the content, should have least spelling errors, if it wants to be listed in top search engines. Again this search depends on the knowledge and language skill of the searcher. People search for particular words in search engines; if you use a single variety of word then you might miss that visitor. Even single meaning words if misspelled can't give the desired search engine results. For example if you search for a word "generalized humor", would you search for both "generalized humor" and "generalized humor"? Most people use simple search terms, when they know there are variant spellings.
But there are few terms which people spell wrongly, and search engines then give them result according to the search word. Though search engine like Google suggest the correct word at the top of the page but some pages are still displayed as per the wrong word. Hence, if there are sites which have those misspelled words then they will be listed and you might lose your potential visitor. This article will give you an idea of using words in your content so that there will be least chance of missing visitors.